This specification relates to determining resource quality based on resource competition.
The Internet enables access to a wide variety of resources, such as video or audio files, web pages for particular subjects, book articles, or news articles. A search engine can identify resources in response to a user query that includes one or more search terms or phrases. The search engine ranks the resources based on their relevance to the query and importance and provides search results that link to the identified resources, and orders the search results according to the rank.
For example, search results can be ranked based on signals and scores related to the resources identified by the search results, such as relevance scores that indicate the relevance of a particular resource with respect to a query, or an authority score that is a measure of relative importance of a resource relative to other resources. Signals may also be used to affect the ranking of resources. For example, a geographic signal may indicate that a particular resource should be ranked higher for users who send a query from the United States than for users who send the same query from Canada. Many other signals can be used to rank resources.